1. Field of the Invention
The present invention relates to a parallelogram shaped or a straight beam type strain gage load converter, which is able to deliver an accurate measurement value even when the load point is located at a position apart from the main axis of the beam of the load converter.
2. Description of the Prior Art
In a conventional load converter of this type, four strain gages are mounted at positions where the concentrating stress occurs. The strain gages are electrically connected in series to form a Wheatstone bridge. If a load is applied to the load converter, it deforms by the applied weight. This deformation causes strain in the converter. By arranging the bridge circuit to balance at no load condition, the deformation by the applied weight is detected using an unbalanced condition of the bridge. The amount of unbalance is in proportion to the applied weight, so that the applied weight is detected from an electric output of the bridge.
In such a conventional load converter, the cross-section of the beam is generally square or rectangular shape. This type of conventional load converter has a drawback in that a measurement error may result according to location of application of the load and thus the load point should be limited only at a certain area. This means that although no measurement error results by shifting the load point along the main axis of the converter, a big measurement error results by shifting the load point normal to the direction of the main axis.
Recently such a load converter has been used in an electronic balance, in which a load converter is provided together with a mount for the load plate and the load plate is directly secured to the mount. In such an electric balance we noted disadvantages in that although no measurement error causes by shifting the load along the main axis of the plate which is parallel to the main axis of the load converter, a big measurement error results by shifting the load point in a direction normal thereto.
The present invention has for its object to mitigate the aforementioned disadvantage of the conventional load converter.